Which statement about Acinetobacter baumannii is true?

Which statement about Acinetobacter baumannii is true?

• A. Requires cysteine
• B. Is oxidase negative
• C. Ferments glucose
• D. Does not grow on MacConkey agar

Answer: (B)

Acinetobacter baumannii is oxidase negative, a hallmark used to distinguish it from oxidase-positive Gram-negative rods like Pseudomonas. The oxidase test detects cytochrome c oxidase; a negative result means this enzyme is absent, so the reagent does not change color. This organism is a non-fermenter of glucose, so it does not produce acid from glucose by fermentation. It can grow on MacConkey agar as a non–lactose–fermenting colony, which fits its profile as a Gram-negative, non-fermentative pathogen. It does not require special nutrients like cysteine for growth. So, the statement about being oxidase negative best describes Acinetobacter baumannii.

Acinetobacter baumannii is oxidase negative, a hallmark used to distinguish it from oxidase-positive Gram-negative rods like Pseudomonas. The oxidase test detects cytochrome c oxidase; a negative result means this enzyme is absent, so the reagent does not change color. This organism is a non-fermenter of glucose, so it does not produce acid from glucose by fermentation. It can grow on MacConkey agar as a non–lactose–fermenting colony, which fits its profile as a Gram-negative, non-fermentative pathogen. It does not require special nutrients like cysteine for growth. So, the statement about being oxidase negative best describes Acinetobacter baumannii.